Real-time Communication System Research Articles

50 m/187.5 Mbit/s real-time underwater wireless optical communication based on optical superimposition

In this paper, an optical pulse amplitude modulation with 4 levels (PAM-4) using a fiber combiner is proposed to enhance the data rate of a field-programmable gate-array-based long-distance real-time underwater wireless optical communication system. Two on–off keying signals with different amplitudes are used to modulate two pigtailed laser diodes, respectively, and the generated optical signals are superimposed into optical PAM-4 signals by a fiber combiner. The optical PAM-4 scheme can effectively alleviate the nonlinearity, although it reduces the peak-to-peak value of the emitting optical power by 25%. A real-time data rate of 187.5 Mbit/s is achieved by using the optical PAM-4 with a transmission distance of 50 m. The data rate is increased by about 25% compared with the conventional electrical PAM-4 in the same condition.

A high-performance dual classifier based packet classification engine on FPGA

Security is one of the key elements of real-time communication systems, especially with the developments in digital communication systems. One of the most crucial networking activities that guards against hacking and unintentional consequences on connected devices is packet classification. The router's and other linked devices' sluggish processing speeds are a problem for implementing real-time packet classification. This paper proposes a novel parallel architecture for packet classification in routers. The design that has been suggested uses the parallelism that modern hardware technologies offer to categorize several packets at once to increase throughput, lower energy usage, and drastically lower latency. The suggested design supports multiple data reads by utilizing Dual Port RAM, or DPRAM. They have low latency performance and allow for fast rate packet lookup, making them the preferable choice for stage memory. The DPRAM provides the data to the packet scheduling module. The packets are received concurrently by the two subsequent packet splitter units. The throughput of packet classification increases as a result. In this paper, a parallel packet categorization architecture using FPGA is explored for maximizing throughput and maintain allowable latency while preserving low energy consumption. The classifier has the lowest energy efficiency of 7.2nJ and less latency of 58 ns. Its throughput may reach 668 MPPS (million packets per second).

VOICE CHAT WEB APP USING WEBRTC

Technology improvements have made it possible to communicate more effectively. New technologies have improved existing communication routes. Some real-time communication systems include limitations, such as the need for additional software plugins and downloads to enable real-time communication, as well as security problems. Web Real-time Communication (WebRTC) is a technology that may be able to assist in the resolution of these issues. Thanks to advancements in internet technology, people may now easily access the internet. With the help of technological improvements, the internet is providing an increasing variety of services, all of which can be virtualized. People's internet communication has become ingrained in their daily lives. People used to communicate with one another by exchanging voice chat messages via the internet.In order to achieve scalability, the platform also makes use of cloud computing. The iterative platform architectural design is revealed, as well as some preliminary scalability analysis results.

Long-Distance, Real-Time LED Display-Camera Communication System Based on LED Point Clustering and Lightweight Image Processing

LED displays can be used to realize the dual functions of display and communication simultaneously. However, existing LED display-based visible light communication (VLC) systems suffer due to their short transmission distance and are not practical. A long-distance, real-time display-camera communication (DCC) system is proposed in this paper. First, a LED-DCC point clustering scheme is proposed to increase the transmission distance by clustering multiple adjacent LED display points for improving the quality of the VLC signal captured by an image sensor. Then, a lightweight, back-forth, fast image processing algorithm is proposed to reduce the introduced additional computational complexity caused by point clustering and enhance the reliability of information extraction from the real-time captured images/video frames. The experimental system was implemented with a 2.2-inch 16 × 16 point LED display and the CMOS camera on the smartphone. Experimental results show that the proposed system can achieve a maximum data transmission distance of 7 m under a bit error rate (BER) of 0.5, which is about 9 times that of the previous LED-DCC system, and can achieve a data transmission distance of 175 cm under the 7% forward error correction (FEC) limit, which is about 12 times that of the previous LED-DCC system. Additionally, the decoding latency for extracting information from each video frame is only 13.26 ms, which guarantees real-time data reception.

Full-duplex wireless deep ultraviolet light communication.

With recent advancements in deep ultraviolet (DUV) light-emitting diodes (LEDs) and solar-blind photodetectors, wireless DUV light communication is emerging as a novel technique, which can extend transmission ranges and avoid solar interference. Herein, a full-duplex, real-time wireless light communication system using 275 nm DUV LEDs is proposed. We adopted high-power DUV LEDs and designed a high-speed transmitter, a high-sensitivity receiver, and a main processing unit for the system. Furthermore, the DUV communication system, using a Reed-Solomon (RS) encoder and an on-off keying (OOK) modem with frequency control, achieves a 10 Mbit/s bidirectional data transmission rate within 5 m in free space, while a full-duplex video communication link is formed. The encapsulated DUV communication system described in this Letter provides a feasible scheme for confidential and anti-electromagnetic interference communication in Internet of Things (IoT) applications.

Three-dimensional holographic communication system for the metaverse

We demonstrate a real-time three-dimensional communication system integrating the capture, hologram generation, transmission and display. The point cloud of a 3D scene is captured by a structured light camera and a light field camera. Phase-only computer-generated holograms are calculated by the layer-based angular spectrum method based on rendered depth images and shading images. The dynamic reconstruction of phase-only holograms is realized by a dynamic 4K liquid crystal spatial light modulator. The framerate of 20 fps and the latency of 0.1 s are realized, which can be satisfied by the 5G network. We suggest that this system is a potential solution to telepresence in the metaverse.

Photonics based frequency hopping spread spectrum system for secure terahertz communications.

Terahertz (THz) spectrum (100 GHz-10 THz) is considered the next frontier in the design of high-speed wireless communication systems. While the high-power THz sources have commercially become available, it increases the possibility of developing THz jammers to disrupt the THz communication link. Therefore, the development of novel anti-jamming solutions is the need of the hour. In this work, we present the photonics-based THz communication system and demonstrate the frequency hopping spread spectrum (FHSS) technique which acts against the single/multi-tone jamming attack in the frequency window of 110 GHz-170 GHz. By tuning the output wavelength of the distributed feedback lasers, the THz carrier frequencies are swept back and forth within the scanning window. The frequency tuning range was measured for different scanning rates of the laser which decreases rapidly with the increase in the scanning rate. Next, we demonstrate the THz FHSS technique in a real-time communication system by transmitting a 6 Gbps NRZ signal in both wireless and THz-fiber-based links within the link distance of 1.75 m. We experimentally found that the measured bit error rate in the THz FHSS system is the time average of the measured BER for individual carrier frequencies within the hopping frequency window. By combining with the forward error correction codes and by using the tunable filter in the receiver, we believe that the proposed technique will offer a novel and compact solution against the single/multi-tone jammer for high-bit rate THz communications.

High Accuracy Software-Based Clock Synchronization Over CAN

In distributed real-time communication systems, common knowledge of the global time is crucial. It prevents message violations on the bus and allows independent components to collaborate within a real-time system on a timely basis. Systems with hard real-time requirements need to have high precision and accuracy of time. This is achieved by hardware-supported frame time-stamping mechanisms as found in dedicated protocols, such as time-triggered CAN (TTCAN), Flexray, and time-sensitive networking (TSN)-enabled Ethernet. However, many microcontroller units are not specifically designed to provide such a hardware-based solution at the communication interface. Therefore, a software-based implementation of the time synchronization algorithm is needed. Nevertheless, some commercial off-the-shelf (COTS) microcontroller units already provide an IEEE 1588-enabled Ethernet interface, including a high-precision timer module with rate correction. This module can be used for time synchronization purposes to align a set of distributed clocks via various communication interfaces. This article investigates the accuracy of software-based and hardware-supported time synchronization algorithm over the controller area network (CAN) protocol using a COTS microcontroller. As a result, we present identified jitter and delay sources as well as the achieved time accuracy. We show that using an advanced timer module combined with additional system knowledge allows submicrosecond precision and accuracies.

Design and Implementation of More Than 50m Real-Time Underwater Wireless Optical Communication System

In this paper, the mathematical model of underwater wireless optical communication (UWOC) is built, the design method and implementation process of the system are described, and the related variables in the system design are quantitatively analyzed, which provide a theoretical basis for the system implementation and experimental verification. In the process of system implementation, three methods are proposed. In the first method (Atmospheric equivalent channel), the underwater channel can be equivalent to the atmospheric channel with the same channel attenuation, so that the power budget verification can be carried out before the system is watertight, and the flexibility of system debugging can be improved. Water quality has a great influence on UWOC, so water quality measurement in uncharted water has become a critical technology. The second method (Water quality measurement) can measure the attenuation coefficient and attenuation of unity distance (AUD) through communication experiments. The system designed in this paper can achieve 32 m/80 Mbps communication in the artificial pool (Firewater, the AUD is 0.55 dB/m by the second method), and the bit error rate (BER) is 8.6×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−6</sup> . Since the target scene is the deep sea, to reduce the difficulty of the experiment, the third method (Calculation of distance in the deep sea) can calculate the communication distance of the deep sea according to the communication distance of the experimental water. The system can complete more than 50 m/80 Mbps communication in deep sea (The AUD is 0.25 dB/m), and the BER is less than 1×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−5</sup> .

RT-SDN: Adaptive Routing and Priority Ordering for Software-Defined Real-Time Networking

In this article, an adaptive real-time communication system is proposed that leverages the software-defined networking (SDN) paradigm to provide end-to-end deadline guarantees. SDN is an emerging networking paradigm that allows control of the network through directly programmable software controllers, offering the flexibility to manage and optimize network resources dynamically. By utilizing these SDN features, a novel networking system, called RT-SDN, is presented that can effectively support real-time communication through cooperative routing and scheduling. To this end, we present a highly efficient routing algorithm that can adaptively reconfigure the routes of existing flows to find bandwidth-guaranteed routes for all flows. We then introduce a new priority assignment scheme that can achieve better deadline guarantees (i.e., better schedulability). In addition, RT-SDN allows routing and scheduling to operate together by employing a feedback loop between them. We implemented a prototype of RT-SDN as an SDN controller and deployed it on a testbed network of 30 BeagleBone devices. Our experiment results show that RT-SDN can be deployed in real-world commodity networks to provide end-to-end deadline guarantees, and the proposed schemes collectively improve the schedulability to a significant degree.

A WebRTC Based Video Conferencing System with Screen Sharing

Abstract: With the modern and rapid development of the internet, people's connections are more important than ever, and they're looking for new ways to communicate with one another in real time. WebRTC is a futuristic technology that enables realtime communication in audio, video, and data transmission through web browsers without the need for a plugin by using JavaScript APIs (Application Programming Interface). In this paper, we present a web peer-to-peer real-time communication system that allows users to communicate across a communication channel with high-speed data transmission using WebRTC technology, HTML5, and a Node.js server address. The outcome demonstrates that the system is stable, fully functioning, and secure. Keywords: WebRTC, Vide o Conferencing Application, Peer to Peer

Measuring Objective Visual Quality of Real-Time Communication Systems in the Wild

During the outbreak of epidemic diseases, the importance of real-time communication (RTC) systems dramatically increases. People use RTC systems for communicating with others, presenting projects, attending online courses, and sharing videos. With different network conditions, applications, and scenarios, how to choose an appropriate system for high-quality RTC is an open question. To the best of our knowledge, there is no general and unified method to comprehensively evaluate the performance of the publicly available RTC systems. In this paper, we systematically evaluate several performances of RTC systems. Our method treats systems as a black-box, which can be easily adapted to other systems. Our method is also available for other video transmission systems, such as streaming and live broadcasting systems. According to our measurement method, we evaluate three web-based and three software-based RTC systems on two video conferencing (VC)-based and two screen sharing (SS)-based scenarios. We measure the received video quality (graphical quality and frame rate) at the receiver, the upload bitrate at the sender, and four usages of local resource. Furthermore, we propose a new metric to measure the ability of the system to handle insufficient bandwidth situations. Our proposed metric is the first one directly measure the ability of the rate adaptation mechanism for RTC systems. We expect the measurement method, the metric, and our findings can help system development in the future. Our detailed analysis reveals that (1) the software-based systems are more efficient than the web-based systems for bitrate usage; (2) the web-based systems are more tolerant to insufficient bandwidth conditions than the software-based systems; (3) the studied RTC systems currently are not designed for the scenario of sharing dynamic videos because of their low-frame-rate strategy, which limits the usage; and (4) decreasing graphical quality is more likely to be recognized than decreasing the frame rate. Frame rate adjustment for rate adaptation can be considered.

Design a Real-time Communication System using 3CX Software-based Private Branch Exchange Phone System on Raspberry Pi Device

With the advancement of technology, the telephone network has become the primary mode of communication worldwide, and private businesses have increased their reliance on telephone communication. Many organizations choose to establish their own service in order to manage internal calls. Voice over Internet Protocol (VoIP) is one of the emerging technologies that may provide low-cost service with high-quality and availability. VOIP technology enables the transfer of multimedia data such as audio and video. While some VoIP services require a computer or a dedicated VoIP phone, others allow you to make VoIP calls using your landline phone via a special adaptor. Rather than using a traditional private branch exchange (PBX), we used a Raspberry pi, which is a set of credit card-sized single-board computers, as a server for handling voice and video call communications over a wired or wireless LAN network while monitoring the entire system. Wireshark is a software application that is used to capture packets in a network and present information about certain packets in as much detail as possible.

A Hybrid-ARQ Method with Adaptive Receiving Buffer Duration in Real Time Video Streaming

To decrease end-to-end delay for streaming media over internet, the transmission method based on best-effort model is always employed in Real Time Communication (RTC) system. However, the packet-loss, jitter and congestion occur frequently because the quality of transmission cannot be guaranteed, which causes lag and splash of video. Therefore, an optimized hybrid Automatic Repeat Query (ARQ) solution with adaptive receiving buffer duration is proposed to guarantee the quality of video transmission. In the method, the loss rate was used to adjust the buffer duration and calculate the redundancy for Forward Error Correction (FEC). The results show that the method in this paper gains lower end-to-end delay and better Mean Opinion Score (MOS) values while ensuring higher fluency in weak network scenarios.

THE DIFFERENCE BETWEEN SYNCHRONOUS AND ASYNCHRONOUS ONLINE LEARNING COMMUNICATION DURING COVID-19 PANDEMIC

Online learning is available in various ways and methods. To find out the difference between online communication and material presented, it must be appropriate so that it can be well received by students. For that, every university must prepare well. Learning online communication that is not ready can automatically disrupt the course of teaching and learning activities. Differences in Synchronous and Asynchronous Online Learning Communication. Synchronous communication is a learning communication carried out in a real time communication system. Lecturers can deliver material in class directly to students. Synchronous online, lecturers can still do virtual learning by online class media. Asynchronous communication is learning communication that is not limited in time. In the meaning lecturer provides material that can be used as a reference for students. The material can be learn by students in the form of PPT files, PDFs, and videos. The Covid-19 pandemic has affected almost all aspects of human life, to break the chain of virus transmission, Indonesian government take of health protocol regulations. The condition of education has huge impact. However, education must continue. Learning process during in emergency is carried out by Synchronous and Asynchronous learning

ECOVID19 – Development of Ontology-based Clinical Decision Support System for COVID-19

Introduction: Humankind is passing through a period of significant instability and a worldwide health catastrophe that has never been seen before. COVID-19 spread over the world at an unprecedented rate. In this context, we undertook a rapid research project in the Sultanate of Oman. We developed ecovid19 application, an ontology-based clinical decision support system (CDSS) with teleconference capability for easy, fast diagnosis and treatment for primary health centers/Satellite Clinics of the Royal Oman Police (ROP) of Sultanate of Oman.Materials and Methods: The domain knowledge and clinical guidelines are represented using ontology. Ontology is one of the most powerful methods for formally encoding medical knowledge. The primary data was from the ROP hospital's medical team, while the secondary data came from articles published in reputable journals. The application includes a COVID-19 Symptom checker for the public users with a text interface and an AI-based voice interface and is available in English and Arabic. Based on the given information, the symptom checker provides recommendations to the user. The suspected cases will be directed to the nearby clinic if the risk of infection is high. Based on the patient's current medical condition in the clinic, the CDSS will make suitable suggestions to triage staff, doctors, radiologists, and lab technicians on procedures and medicines. We used Teachable Machine to create a TensorFlow model for the analysis of X-rays. Our CDSS also has a WebRTC (Web Real-Time Communication system) based teleconferencing option for communicating with expert clinicians if the patient develops difficulties or if expert opinion is requested.Results: The ROP hospital's specialized doctors tested our CDSS, and the user interfaces were changed based on their suggestions and recommendations. The team put numerous types of test cases to assess the clinical efficacy. Precision, sensitivity (recall), specificity, and accuracy were adequate in predicting the various categories of patient instances.Conclusion: The proposed CDSS has the potential to significantly improve the quality of care provided to Oman's citizens. It can also be tailored to fit other terrifying pandemics.

Refiner GAN Algorithmically Enabled Deep-RL for Guaranteed Traffic Packets in Real-Time URLLC B5G Communication Systems

Ultra-reliable and Low-latency Communications (URLLC) is expected to be one of the most critical characteristics Beyond fifth-Generation (B5G) cellular networks with stringent low latency and high-reliability requirements. The Deep Reinforcement Learning (deep-RL) framework has been applied to predict the optimization of a Resource Block (RB) and minimize Power Allocation (PA) to guarantee a high End-to-End (E2E) reliability and low E2E latency under rate constraints. This paper proposes a novel Policy Gradient-based Actor-Critic Learning (PGACL) algorithm to optimize the policy gradient for optimal rate allocation to solve the RB, minimize power, and guarantee a solution for URLLC scheduling. The purpose of a PGACL algorithm is to provide a good policy with a closer convergence rate and a low computational cost depending on the reduced action space for every user. URLLC systems need to operate in highly reliable systems and account for extreme network conditions. Therefore, we proposed the refiner Generative Adversarial Networks (GANs) that apply enough extreme events for the deep-RL agent to generate synthetic data with high reliability similar to real data based on the regulated number of extreme events in the dataset. This refiner GAN method enables a deep-RL approach to generate large amounts of data practically used in real-time operations. Simulation results showed that the proposed deep-RL for refiner-GAN can omit the transient training time and develop deep learning based on a controlled set of unlabeled real traffic at a relatively short time. Furthermore, the refiner GAN demonstrated 99.9999% reliability and E2E latency of less than 1.4ms.

Project starline

We present a real-time bidirectional communication system that lets two people, separated by distance, experience a face-to-face conversation as if they were copresent. It is the first telepresence system that is demonstrably better than 2D videoconferencing, as measured using participant ratings (e.g., presence, attentiveness, reaction-gauging, engagement), meeting recall, and observed nonverbal behaviors (e.g., head nods, eyebrow movements). This milestone is reached by maximizing audiovisual fidelity and the sense of copresence in all design elements, including physical layout, lighting, face tracking, multi-view capture, microphone array, multi-stream compression, loudspeaker output, and lenticular display. Our system achieves key 3D audiovisual cues (stereopsis, motion parallax, and spatialized audio) and enables the full range of communication cues (eye contact, hand gestures, and body language), yet does not require special glasses or body-worn microphones/headphones. The system consists of a head-tracked autostereoscopic display, high-resolution 3D capture and rendering subsystems, and network transmission using compressed color and depth video streams. Other contributions include a novel image-based geometry fusion algorithm, free-space dereverberation, and talker localization.

High-speed real-time visible light communication system based on InGaN/GaN-base multi-quantum well blue micro-LED

High-speed real-time visible light communication system based on InGaN/GaN-base multi-quantum well blue micro-LED

Analysis of Ultra Wide Band OFDM Communication System through IEEE802.15.4a in Wireless Communication

This paper uses simulation to evaluate the performance of a UWB communication system with an accurate channel model. A cost-effective prototype model of a real-time UWB communication system. This paper presents a UWB multiband OFDM system for various frequency ranges.Channel subgroups provide various models for the various frequency ranges of IEEE 802.15.4a. The UWB frame repeats from 2 to 10 GHz and provides 8-channel models for indoor and outdoor LOS (line-of-sight) and NLOS (no-line-of-sight) environmental conditions.The uniqueness of Task Group 4a channel models and UWB-enabled frameworks are reviewed and evaluated against a number of channel models.